Measurement-indicating instrument.



F. STIMSON.-

MEASUREMENT INDIGATING INSTRUMENT.

APPLIOATIDN FILED MAIL 12, 1910.

Patented Apr. 25,1911.

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FRANK G. STIMSON, OF PROVIDENCE, RHODE ISLAND.

MEASUREMENT-INDICATING INSTRUMENT.

Specification of Letters Patent.

Patented Apr. 25, 1911.

Application filed March 12, 1910. Serial No. 548,780.

To all whom it may concern:

Be it known that I, FRANK G. STIMSON, a citizen of the United States,residing at Providence, in the county of Providence and State of RhodeIsland, have invented certain new and useful Improvements inMeasurement-Indicating Instruments, of which the following is aspecification.

My invention relates to portable tools or instruments constructed andadapted, when in use, for accurately indicating variations oreccentricity in a piece of work from a true center, and it consists incertain novel features of construction and arrangement of the parts, allas more fully hereinafter set forth and claimed.

The objects sought to be attained are to produce a simple andcomparatively inexpensive tool of the general type or character referredto and possessing a greater degree of efliciency and accuracy, as wellas adaptability to a more extended range of work than other tools orcenter measurement indicators heretofore devised. That is to say, myimproved indicating instrument is capable of being easily and readilyused upon machines having revoluble cutter-carrying spindles, as forexample milling machines, boring machines, drill-presses, etc. In saidinstrument I employ an endwise movable graduated indicator-bar, mountedand disposed so that the readings are visible under any and allconditions when the device is in service. The endwise slidable barelement constitutes a novel and important feature of the presentinvention. In fact, the device may be termed a sliding-bar centerindicator for milling machines.

In the accompanying sheet of drawings, Figure 1 represents a front sideelevation of my improved center indicating tool complete, the partsbeing in the normal or central position. Fig. 2 is a correspondingelevation of the device, the front plate or cover being removed. Fig. 3is a vertical central sectional view, taken substantially on line 3 3 ofFig. 1. Fig. 4 is an enlarged sectional view showing more clearly thecorresponding parts represented in Fig. 3. Fig. 5 is also an enlargedsectional view showing more clearly the corresponding parts representedin Fig. 3. Fig. 6 represents in reduced scale a front elevation of thetool detachably connected to the revoluble vertical spindle of a millingor boring-machine, and

showing its application in ig work u on a button or to a cylindricalpiece 0 stationary work for determining the accuracy of the lattersposition with respect to the center of the work-spindle. Fig. 7 is afront view of the attaching device itself (shown in Fig. 6), theindicating-tool being omitted. Fig. 8 is a corresponding top plan view,and Fig. 9 is a side view of a holder member constructed to fit thetool-post of a lathe, the holder being adapted to have the indicatortooladjustably and removably secured to it.

The following is a detailed description and manner of operation of thecenter-indicator tool forming the subject of this application forpatent.

Again referring to the drawings, A designates the tool as a whole asmade of steel or other suitable metal. It is provided with a chamberedhousing or casing substantially uniform in depth or thicknessthroughout, the same consisting of the recessed back or base member aand the thin, flat front plate or cover 6, secured thereto by screws m.The shank portion of the casing is comparatively long and narrow andterminates at its upper end in the enlarged chamber head part al havingthe indicator bar B, pro vided with two independent series ofgraduations g, mounted and longitudinally slid able therein. The face 9"of the upper end of the part a is trued off so as to register accuratelywith the zero or median line 0 of the gage when the several movableelements of the device are in the central or normal position. See Fig.2.

It may be stated here that, as drawn, the relative leverage of the twoconnected main or primary and secondary swinging arms or levers c and dto each other (soon to be described) and to the contact point member hand bar B are such that the ratio of movement is to l, the divisions orreadings formed on the bar being correspondingly multiplied, or, inother words, a lateral variation of the point member la from the true ornormal central position would cause the bar to move correspondingly. Ifthe point swings outwardly (see arrow 1 Fig. 2) say one-thousandth of aninch, the bar will move upward from the zero position until the figure.1 of the lower gage is exposed and registers with the face 1", therebyclearly and of an inch. Conversely, if the point is swung inwardly (seearrow 2), a corresponding distance, the bar will thereby be moveddownwardly until the figure 1 of the upper gage registers with thesurface '2". The said lever member 0 extends downwardly in the casing,its lower end having a screw-threaded hub a bored to fit the pivotpin 6fixed in the base a, a screw 6 (Fig. l) tapped into the front end of thepin serving to keep the lever in position laterally. The said contactpoint member 72. may have any suitable shape desired; the drawingsrepresenting it as being spherical. It is removably secured to a holderelement f bored to fit the said hub 0 and is axially movable thereon, amilled nut 6 cooperating with the screw-threaded part of the hub, beingemployed for clamping the member 72 in position when adjusted. Theadjacent portion of the cover is cut away at b to receive the nut. Theupper end of lever c is forked and provided with an open central slot 0engaged by the short transverse pin 6Z2, suitably vfixed in the thinhorizontal barcarrying lever d, mounted in the upper or head portion aof the indicator. The said arm or lever d is mounted to swing on ashouldered pivot-pin d fixed in the base member a, a screw 0Z tappedinto the pin maintaining the lever in position. The outer or free end oflever cl extends through the indicator-bar and is operatively connectedto it by means of a pin d passing transversely through both members, thelever element having an open radial slot d for the pin; the length ofthe slot exceeding the versed sine of the levers angular movement, allas clearly represented.

I prefer to further provide the lever cl with a wire spring 8, having acoil 8 one end of the wire being mounted in a pin d of the lever, itsother end passing through a hole 8 formed in the inner head of ashouldered stud n, movably mounted in the cover I); the axis of the studand said pin d being in alinement with each other, see Fig. 5. A thin,flat outer spring-plate n is fixed to the hub of stud it, its free endhaving a headed pin a secured thereto and extending into a shallow holen formed in the cover 6. By means of this construction, the normaltendency of the spring 8 in the position shown is to swing the lever dand ar B upwardly, while at the same time insuring contact of the pointIt with the surface of the work when the instrument is used forindicating, corresponding with arrow direction 1, Fig. 2. When it isoppositelyemployed (see arrow direction 2, Fig. 2) the pin 91. iswithdrawn from hole a and swung downwardly until it springs into theregistering hole n, Fig. 1, thereby correspondingly reversing the normalaction of spring 8 with respect to its former position.

The center screw a tapped into stud 12 serves to maintain the plate a inplace laterally upon the stud.

In Fig. 6 my improved center indicator instrument A is represented asbeing employed in connection with the revoluble vertical spindle D of,say a milling machine. In this case the indicator is adjustably securedto an elongated slotted frame 19, in turn adjustably clamped to a holdermember 7), drilled to receive the lower reduced end portion 2' of theplug member of the vertical spindle. The holder is secured to thespindle by means of a screw '0 Fig. 8, and to the frame itself by a nut2' (Fig. 6) fitted to the screw-threaded stem 2' passing through theframe. See also Figs. 7 and 8. The indicator has a fixed, screw-threadedstem a extending at right angles from the back of the base member a(Fig. 3), provided with a nut a thereby adapting it to be clamped to theelement 39 or other analogous supporting means. The frame 39 is providedwith a pair of dogs or collars, u, if, slidably mounted therein, eachhaving an extension on its under side tapped to receive the respectiveend portion of a right and left-hand screw u the latter being interposedbetween the collars. By means of this arrangement the indicator may bevery accurately set or adjusted with respect to the spindle and work.The stem 61, extends through the collar u, the nut a securing it inplace. In order to positively prevent the indicator from moving axially,the collar is provided with a fixed dowel-pin a adapted to extend into acorresponding hole a formed in the base.

Now, upon rotating the spindle D, the indicator itself having beenpreviously. at tached to it and approximately adjusted, the pointelement It, contacting lightly with the normally stationary cylindricalarticle or piece of work 'w (Fig. 6) to be tested will, in cooperationwith the compound levers c, d, and spring 8, cause the bar B to slideendwise up or down in the head a correspond ing with the slightvariation, if any, of the center of the work from the true orspindlecenter, thereby at the same time exposing the readings of thegage or index g, which may then be readily observed and noted. Theindicator may be employed for determining the accuracy of thecylindrical surface; that is, whether its periphery is absolutelyconcentric with the center, and also for accurately centering the workwith respect to cutting tools, as for example, a drill mounted in arevoluble spindle, or even a stationary tool cooperating with revolvingwork.

The indicator may be used in connection with a lathe. In such case, itsscrewthreaded stem a is inserted through a hole k (Fig. 9) formed in thefree end of a holder 70, in turn adapted to be secured in the usualtool-post. The nut a may be employed for securing the indicator inposition when adjusted.

I claim as my invention and desire to secure by U. S. Letters Patent:

1. As an improved article of manufacture an indicator instrument of thegeneral character described, the same comprising an elongated casing orhollow body having one end portion provided with a lateral extension, anindicator-bar movably mounted in and rojecting through said extension,an angu arly movable member or contact element pivotally mounted in theother end portion of the casing adapted when in use to engage the workor object being tested, and movement-multiplying mechanism located inthe casing 'and operatively connected with said indicator-bar andcontact element, for the purpose set forth.

2. The combination, in a center-indicator instrument of the characterdescribed, of a longitudinally movable scale-bearing bar, a pivotallymounted lever having its free end engaging the bar, a pivoted main leverhaving its longer arm in operative engagement with the first-namedlever, and a contact element secured to the main lever at a pointrelatively close to the latters fulcrum.

3. A portable indicator instrument of the character described, adaptedto be detachably secured to machine tools, as for example, lathes,boring-machines, milling machines, etc., the same consisting of a hollowcasing, a comparatively long lever member fulcrumed in one end portionof the casing, a relatively short point element adjustably secured toand movable with the lever, a suitably graduated, longitudinally movableindicator-bar mounted in and extending through the walls of the oppositeend por tion of the casing so that upon movin said bar its graduationsare exposed and may be read with respect to a stationary or fixed part,and a fulcrumed member (Z disposed at substantially right angles to thelongitudinal axes of and operatively connecting said lever and barmembers, constructed and arranged whereby the angular movements of thepoint element cause the said bar to move simultaneously with it apredetermined greatly increased distance.

4. In an indicator instrument of the character described, a suitablecasing, and an indicator-bar longitudinally slidable therein, having itssurface provided with a pair of oppositely disposed index scales, eachreadable from a central or median zero line, in combination with amovable point element adapted, when in use, to engage the work beingtested, a relatively long lever having said point element securedthereto, and a fulcrumed member 41 in operative engagement with saidlever and indicator-bar arranged at substantially right angles to thelongitudinal axes of both, substantially as described. I

5. In an indicator instrument of the char acter described, thecombination of an endwise slidable indicator-bar, provided with indexgraduations, a pivotally mounted point or contact element, amovement-multiplying means in operative engagement with the bar andpoint members, a stud, a spring cooperating with the bar and mounted inthe stud adapted, when in use, to press the bar in one direction, and atthe same time serving to press the point element against the work beingtested, and means, consisting of an angularly movable plate having saidstud secured thereto and a locking-pin carried by the plate, forchanging the position of the spring so as to press the bar in adirection contrary to its former one when the relation of the pointelement to the work is correspondingly changed.

In testimony whereof I have afiixed my signature in presence of twowitnesses.

FRANK Gr. STIMSON.

Witnesses:

GEO. H. REMINGTON, CALVIN H. BROWN.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. G.

